Stair Calculator
Measure the total rise from the finished floor (or ground) at the bottom to the finished floor or deck surface at the top. The calculator splits it into equal risers no taller than the limit you set.
The International Residential Code allows risers up to 7¾ in and treads at least 10 in deep. Every riser in a flight should be within ⅜ in of the others.
How it’s calculated
- Risers = total rise ÷ maximum riser, rounded up. Riser height = total rise ÷ risers.
- Treads = risers − 1 (the top floor is the last step). Total run = treads × tread depth.
- Stringer length = √(total rise² + total run²).
Questions
- How many stairs for a 9 foot ceiling?
- A 9 ft ceiling usually means about 108 in floor to floor with the floor framing, which takes 14 risers of about 7.7 in.
- What is the ideal stair rise and run?
- A riser of about 7 to 7½ in with a tread of 10 to 11 in is comfortable. A common rule: two risers plus one tread should be 24 to 25 in.